Pyrrolo[3,4-c]pyrrole-1,4-dione, 2,5-dihydro-3,6-diphenyl-

Endpoint summary

Description of key information

Acute oral toxicity: LD50 > 2000 mg/kg bw; OECD 401, CIBA 1986a
Aucte dermal toxicity: LD50 > 2000 mg/kg bw; OECD 402, CIBA 1986b
Aucte inhalation toxicity: LD50 > 2.25 mg/L; OECD 403, Ciba 1991a and b (read-across)

Additional information

There are valid in vivo data available for the assessment of the acute oral and dermal toxicity potential of Pyrrolo(3,4-c)pyrrole-1,4-dione, 2,5-dihydro-3,6-diphenyl-.

 Oral: In an acute oral toxicity study (OECD 401, CIBA 1986a), groups of fasted 9 - 11 week old rats (5/sex) were given a single oral dose of the test substance in polyethylene glycol 400 at 5000 mg/kg bw. and observed for 14 days. No mortality occurred and normal body weight gain were found in this study. The following symptoms were found: sedation, rales, dyspnea, curved body position, ruffled fur, extremities: red discolored (test article). All rats had recovered within 3 observation days. At autopsy, no macroscopic organ changes were observed.

Dermal: In an acute dermal toxicity study (OECD 402, CIBA 1986b), groups of 9 - 11 week old rats (5/sex) were dermally exposed to the test substance diluted in polyethylene glycol 400 for 24 hours to 10% of body surface area at 2000 mg/kg bw. Animals then were observed for 14 days. No mortality occurred and normal body weight gain were found in this study. A reddish discoloration of the treated skin was observed in all rats during the observation period which is attributed to the test article. No other signs of local or systemic toxicity was observed in the treated animals At autopsy, no deviations from normal morphology were found.

Inhalation: For read-across justification, it is referred to chapter 5.1.3 (toxicokinetic information).

In the key study, an acute inhalation toxicity GLP conform test, performed according to OECD Guideline 403, a nose inhalation system was used to expose 5 Wistar rats per sex to an aerosol at a concentration of 2.25 mg/L for 4 hours (Ciba, 1991a, b).

The animals were observed for a post-dosing period of 14 days for mortality, body weight changes, clinical signs of intoxication and pathological findings. No mortality and no macroscopic findings at necropsy were observed in males and females. It was not possible to generate higher concentrations of the test compound. The exposure to the maximum attainable concentration was thus considered a limit test as stated in the OECD test guideline 403. Clinical symptoms were piloerection, hunched posture and dyspnea. From this, the animals recovered within 5 to 9 days. Histopathological examinations of the lungs revealed minimal congestion, minimal emphysema and minimal and multifocal bronchiolar dilatation in all animals. These changes are common response in rats treated by inhalation with a nuisance dust.

 

In a mechanistic follow-up study the acute lung response, especially acute inflammatory/ cytotoxic responses in the rat lung following a single administration by inhalation of an aerosol for 4 hours was assessed by examination of various biochemical and cellular parameters in bronchoalveolar lavage fluid obtained 24 hours after exposure (Huntington, 1998). The investigation was based on a publication by Lindenschmidt et al.(“The comparison of a fibrogenic and two nonfibrogenic dusts by bronchoalveolar lavage.” Toxicology and Applied Pharmacology, 102, 268 – 281 (1990)). As it is a non-standard study, historical control data was not available.

Measured concentrations were 1.1 mg/L for the test item, the negative control titanium dioxide (nuisance dust) and the positive control Sikron F600 ((also known as HSE Standard Quartz, fibrinogenic agent). The MMAD was 2.5, 2.0 and 2.7 µm for titanium dioxide, Sikron F600 and the test item, respectively. At least 90% of the particles were had a diameter of less than 7 µm. Another control group was exposed to air only. There were no signs indicative of a toxic or irritant effect following exposure to the test compound. Red stained feces and staining of the skin/fur were noted in both sexes post exposure to the test item. Exposure exaggerated respiratory movements were evident in a proportion of rats exposed to the test compound from 15 minutes of exposure. This finding was also apparent after inhalation of titanium dioxide (2 h) and Sikron F600 (15 minutes), respectively, but not the air control.

There were no treatment-related macroscopic findings following the 24 hour post exposure observation period. No effects on lungs weights after exposure to 3,6-bis(4-chlorophenyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione were seen.

After laboratory investigations of bronchoalveolar lavage samples, differences to air control samples were evident in animals treated with the test compound, titanium dioxide and Sikron F600. Biochemical examinations showed thatβ-glucuronidase, N-acetyl-glucosaminidase and lactate dehydrogenase levels in animals exposed to aerosols of the three dust samples were higher than in air control values.

Total protein values as well as the total and viable cell counts were also higher than in air controls.

The order of magnitude of effects was similar for both control dusts and the test item, with the responses to the test item being generally higher than those to both dust controls. The experimental design was set up to test equal particle load in regard to number and size, but the density and the surface area of the particles were not taken into account. Therefore, a quantitative interpretation of the results is not possible. This acute response is typical of the lung response to inert and biologically active particles and it is only several weeks after exposure that the cellular response to inert and biologically active particles differs (Lindenschmidt 1990).

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is not considered to be classified for acute oral, dermal or inhalation toxicity under Directive 67/548/EEC, as amended for the 28th time in Directive 2001/59/EC.

 

Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for acute oral, dermal or inhalation toxicity under Regulation (EC) No. 1272/2008.